PEARCY ET AL.: SUBMERSIBLE OBSERVATIONS OF DEEP-REEF FISHES 



lA-Shallow Rock Habitat. Six transects near 

 the top of the bank (67-76 m) were over a sea- 

 floor predominated by high-relief, massive rock 

 walls often separated by eroded valleys filled 

 with cobble or sand. Four transects were over 

 cobble and flat rock interspersed with patches of 

 mud at depths of 104-149 m. Crinoids {Floro- 

 rnetra serratissirna), sponges, anemones (Metri- 

 dium sp.), hydrocorals, and bryozoans were 

 abundant on exposed rock faces. Basket stars 

 {Gorgonocephalus sp.) were obvious on ridge 

 tops. Rockfishes were the most frequently ob- 

 served fishes, especially rosethorn, small 

 sharpchin rockfishes, and large yelloweye (S. 

 n(berri))ius), and yellowtail rockfishes. 



IB-Shallow Cobble Habitat. Three of the 

 transects were at 122-145 m over cobble and 

 lower rehef rocks interspersed with soft sedi- 

 ments on the northern portion of the bank (Fig. 

 1). Rosethorn, yelloweye, canary (S. pinriiger), 

 and large sharpchin rockfishes occurred near 

 rocks, and zoarcids and longnose skates {Raja 

 rhino) were seen in muddier areas. 



IIA-Deep Mud-Cobble Habitat. Two of the 

 transects were over mud and cobble substrates 

 in deeper water (18.5-220 m and 140-148 m, 

 respectively). Rosethorn, greenstriped (S. 

 elongatus), canary, and yellowtail rockfishes oc- 

 curred in these two transects but were absent in 

 deeper transects over mud bottoms. However, 

 the fishes seen on these transects were similar to 

 mud bottom assemblages because of the occur- 

 rence of several species of flatfishes. Green- 

 striped rockfish and Dover sole, Microsto»ti(s 

 pacificus, occupied soft bottom areas between 

 rocks. 



IIB-Deep Mud Habitat. Six transects were 

 over mud, which was the predominant substrate 

 at the deepest depths, 164-300 m, although oc- 

 casional small rock outcrops or boulders were 

 evident there. Sea urchins, Allocentrotus 

 fragilis; sea stars, Pycnopodia helianthoides; 

 sea cucumbers, Parastichopus californicus; and 

 crabs Lopholithodes foraminatus were common 

 in this habitat. All these invertebrates had very 

 patchy distributions. We saw zoarcids, Dover 

 sole, and unidentified flatfishes on all six of these 

 transects, and hagfish (Eptatretus sp.); rex sole, 

 Glyptocephalus zachirus; slender sole, Lyop- 

 setta exilis; sablefish, Anoplopoma fimbria; 

 poachers (Agonidae); and skates (Rajidae) on 

 most transects. The deep mud habitat included 



some species also seen over shallow rock and 

 cobble as well as species only observed over deep 

 mud and cobble (Table 2). 



The two cobble subgroups (IB and IIA) are 

 probably transitional habitats between shallow 

 rock (lA) and deep mud (IIB). As such they 

 allow comparisons of the occurrence of fishes on 

 similar bottom types at different depths. Yellow- 

 eye and canary rockfish appeared to be more 

 common at shallow than deep cobble, whereas 

 splitnose and greenstriped rockfish, cottids, 

 Dover sole, and other flatfishes were more fre- 

 quently seen over deep than over shallow cobble. 

 Rosethorn rockfish were common in both sub- 

 gi-oups (Table 2). 



Six to 22 different species of nonschooling 

 fishes were identified on individual transects. 

 Interestingly, the fewest species of fishes (6-12) 

 were seen on the shallowest dives, over rocky 

 and cobble bottoms (67-149 m; Habitat I), while 

 the greatest number (10-22) were seen on 

 deeper dives over mud and cobble bottoms 

 (164-299 m; Habitat II) (Table 2; Mann-Whitney 

 U-test, P < 0.01). This difference would be re- 

 duced if the unidentified schooling rockfishes 

 seen in shallow water (see below) could have 

 been included. Average density of nonschooling 

 fishes observed varied greatly (0.02-1.3/m^) 

 within and among habitat types. No difference 

 was found in the densities between Habitat I and 

 Habitat II (Mann-Whitney U-test, P > 0.2). 

 Fish density was highest on dives over slabs of 

 flat rock at 149 m (15A) where large numbers of 

 juvenile rockfishes were seen. 



Rockfishes 



Because rockfishes were the most numerous 

 and diverse family of fishes seen on our dives 

 (Tables 1 , 2) and because they are taxonomically 

 a cohesive group with distinct behavioral pat- 

 terns, they merit special consideration. Most 

 individuals could be categorized into one of four 

 distinct size groups and behavior patterns: 1) 

 schools of small or juvenile fishes, 2) solitary 

 benthic fishes of intermediate size, 3) pelagic 

 schools of large fishes, and 4) large solitary 

 rockfish near the bottom. 



Small Schooling Rockfishes 



We saw 24 schools, comprised of 10 to several 

 thousand small (<10 cm) unidentified reddish 

 juvenile rockfishes, during 5 of the 16 dives. 



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